With Mayor Bill de Blasio’s poll numbers in a prolonged slump, Republican leaders have vowed to put up a strong challenger in 2017. But to compete in strongly liberal New York City, Republicans would most likely need either a candidate of some political celebrity to challenge the Democratic mayor, or at least someone with vast personal wealth to spend on a campaign.

Michel J. Faulkner does not fall into either category.

On Monday, Mr. Faulkner, a Harlem minister who once played football for the New York Jets, began what he described as a marathonlike campaign to unseat Mr. de Blasio, broadly criticizing the mayor’s leadership style and management of the police.

Mr. Faulkner, a Republican, said it was essential to announce his long-shot bid more than two years before the 2017 election. Defeating Mr. de Blasio, he said, would require a full-scale political movement rather than a conventional campaign.

Standing at a busy intersection north of Times Square, periodically drowned out by the noise of construction and traffic, Mr. Faulkner said Mr. de Blasio had proved to be a divisive leader without the charisma to lead a great city.

“I don’t think he really understands the core of who we are as a city — the greatness, the history of this city,” Mr. Faulkner said in an interview. “That’s what I want to be able to tap into.”

A spokesman for Mr. de Blasio declined to comment on Mr. Faulkner’s criticism of the mayor. At an unrelated event on Monday, the mayor shrugged off the Republican’s announcement.

“The more the merrier,” Mr. de Blasio said of his aspiring challengers. “I feel very good about what I have to say to the people of this city over the next two years.”

Mr. Faulkner has sought political office before, challenging Representative Charles B. Rangel in the 2010 election. He won about 10 percent of the vote in an overwhelmingly Democratic district.

Mr. Faulkner has broadcast his intention to run for mayor for months. On Monday, he said that he had already begun knocking on doors in neighborhoods like Bensonhurst and Sunset Park in Brooklyn.

But Mr. Faulkner also acknowledged that his mayoral bid was very much a work in progress. The pastor said he had yet to speak with either of the city’s last two Republican mayors, Michael R. Bloomberg and Rudolph W. Giuliani, about his campaign.

Queried about his ideas for affordable housing, Mr. Faulkner said he would have more specific policy proposals within a year.

Although Republicans intend to back a strong candidate against Mr. de Blasio, the party does not have a deep bench. Speculation so far has focused on Raymond W. Kelly, who was the police commissioner under Mayor Bloomberg, and Eva S. Moskowitz, the charter school executive who was previously elected to office as a Democrat, but has clashed bitterly with Mr. de Blasio over education policy.

Mr. Faulkner is a social conservative who has opposed abortion rights and same-sex marriage. (Asked about his views on same-sex marriage on Monday, Mr. Faulkner said that the mayor of New York City had no role in the issue.)

Still, clad in a pinstriped suit with a blue ribbon pinned to his chest — to show support for the police, he said — Mr. Faulkner said he had the force of personality and the right philosophy of government to lead New York.

Mr. Faulkner, who served on a task force on police relations under Mayor Giuliani, faulted Mr. de Blasio for failing to reassure police officers that he “has their back,” and for alienating the business community.

Mr. Faulkner pledged that he would get along better with Gov. Andrew M. Cuomo, who is a Democrat, than Mr. de Blasio has. The two Democratic leaders have clashed, with increasingly open hostility.

“This governor has been pretty independent of his party,” Mr. Faulkner said. “I have no doubt that I will have a much better relationship, a working relationship, with this governor.”

And if Mr. Faulkner were to advance to a debate with Mr. de Blasio, he would at least be able to challenge the mayor eye-to-eye: At 6-foot-4, Mr. Faulkner is, at most, only one or two inches shorter than Mr. de Blasio.

A version of this article appears in print on , on Page A24 of the New York edition with the headline: Harlem Minister Who Played for Jets Opens G.O.P. Bid to Unseat de Blasio in 2017. Order Reprints | Today’s Paper | Subscribe